The present invention relates to impellers and more particularly to impellers with variable pitch self adjustable blades. Most impellers both driven and driving are exposed to varying operating conditions some of which are unknown or unexpected at the time of the original design. Some of these varying conditions are imposed by characteristics of the flow media others by changes in magnitude and direction of the flow surrounding the impeller. Typical flow media characteristics which might change during operation are density, viscosity, bubbles and solid particles.
In an embodiment where the impeller works in an enclosed area the local speed relative to the impeller blade might be uncertain due to several factors, as in case of a tank the diameter, straight length, liquid level and tank internals.
Another embodiment where the impeller is exposed to an open environment, like a windmill, the design parameters change and require adjustment to the optimum conditions imposed by temperature, wind speed and direction.
Compared to the numerous existing variable pitch inpellers the herewith presented invention has several advantages, it is simple in its mechanical features, has only a few essential parts, it is flexible to adapt to a wide range of applications, it does not require an external power source, sensing instruments or supervision.
The principal object of this invention is to provide for a variable pitch impeller which adjusts the impeller blade angle to the local relative speed between fluid media and impeller blade angle.
Another object of the invention presented is to utilize a simple control surface as sensor to initiate a necessary change in the impeller blade angle.
A further object of the invention is to utilize the control surface to energize the variation in the impeller blade angle.
A still further object is to accomplish a relatively complicated task with only a few mechanical parts.
Other objects, features and advantages of the invention not described herein will become understood from a consideration of the specification with reference to the accompanying drawings forming part thereof.